1. Field of the Invention
This invention relates to a preparation for treating washed laundry in a tumble dryer consisting of a flexible sheet-form material coated with a mixture of active substances for treating laundry.
With the development of automatic tumble dryers, in which washed laundry is dried by heated air, it became possible to carry out the treatment of laundry generally effected during the final rinse cycle of a washing machine in a tumble dryer. The object of treating washed laundry in this way is generally to give the laundry a pleasant soft and full feel, anti-electrostatic properties and an agreeable fragrance. Whereas, in the treatment of laundry in the final rinse cycle, it had always been necessary to use active substances which were completely transferred to the fabrics to be treated in the aqueous wash liquor, the shift of the treatment process to a tumble dryer made it possible to use active substances that were difficult or even impossible to use in aqueous wash liquors. Although, in principle, active substances different from those used in the final rinse cycle can be used in the treatment of laundry in a tumble dryer, the active substances used in the final rinse treatment, namely quaternary ammonium compounds containing 1, 2 or 3 long groups in the molecule derived from ammonia or imidazoline, have hitherto also been used almost exclusively in the treatment of laundry in a tumble dryer. The reason for this is that quaternary ammonium compounds such as these can be synthesized relatively easily and, above all, are extremely effective as fabric softeners.
2. Discussion of Related Art
Various proposals have been put forward for the application of fabric softeners to fabrics in a tumble dryer. For example, it has been proposed to transfer the active substances to the laundry, if desired together with additional auxiliaries, from rigid containers added to the laundry in the tumble dryer. In addition to rigid containers, flexible containers, for example bags, filled with the active substances have also been proposed. However, the most simple and, hence, generally the most common option is the release of the active substances from flexible sheet-form materials. The treatment of laundry in a tumble dryer by flexible sheet-form materials impregnated with active substances is described, for example, in German patent application DE-A 19 55 803. However, depending on the type of sheet-form textile used for impregnation with the active substance, the problem arises that, in the case of substrates having a low adsorption capacity, the fatty active substances are unevenly transferred to the fabrics and leave greasy marks thereon. Other substrate materials of high adsorption capacity, such as for example sponge cloths or foam sheets, do not provide for an adequate release of the active substances so that, where they are used as carriers for the active substances, losses of active substances are incurred in the form of unused active substances.
According to the teaching of DE-A 19 65 470, the disadvantages described above can be overcome by using substrates of medium adsorption capacity as carriers for the quaternary ammonium compounds. However, it was subsequently found that, under certain conditions, it is even possible to use substrates of low adsorption capacity, which have the advantage of high active-substance release, without any marks being left on the laundry. Preparations for the treatment of washed laundry in a tumble dryer, of which the carriers for the fabric softeners include a substrate of low adsorption capacity, are the subject of DE-A 30 03 249.
According to the teaching of DE-A 27 00 512,up to 60% of the softening quaternary ammonium compounds can be replaced by fatty acid esters of a polyhydric alcohol. This has the advantage that the substrates used as carriers for the fabric softeners are not required to have a specific adsorption capacity.
Laundry treatment preparations for use in tumble dryers, of which the active substances are free from quaternary ammonium compounds, are also known. For example, DE-A 25 16 104 describes products of which the active component consists completely or partly of sorbitan esters. However, in the same way as the quaternary ammonium compounds, sorbitan esters cause staining or are characterized by an inadequate release of active substance unless materials of medium adsorption capacity are used as the substrate.
Other fabric softening agents which do not contain any quaternary ammonium compounds are the fatty acid esters of polyhydric alcohols known, for example, from DE 27 00 512. According to the teaching of this patent application, however, they have to be used in conjunction with appreciable quantities (40 to 95% by weight) of cationic fabric softeners of the quaternary ammonium compound type. However, it has recently been found that, on account of their more or less pronounced toxic properties and their poor biodegradability, quaternary ammonium compounds pollute the wastewater which they enter on completion of the rinse cycle or together with the wash liquor of the washing process following the aftertreatment. Accordingly, the problem addressed by the present invention was to provide fabric-softening mixtures for the treatment of washed laundry in a tumble dryer, the mixtures being released and transferred to the fabrics to be treated without staining and at a high rate from a flexible sheet-form material serving as carrier for the active substances and the mixtures being free from quaternary ammonium compounds. Another problem addressed by the invention was to provide a fabric softener or mixture of fabric softeners which, in the production process, would solidify rapidly, i.e. at a relatively high temperature, after application to the flexible sheet-form material to form a layer with a dry feel and would provide the fabrics thus treated with good anti-electrostatic properties.